Add the beans and 4 cups of water in a large pot, cover, on the lowest flame possible. Take the outer skins off the onions and place the whole onion in the covered pot. Do not chop up the onions. Add the whole zucchinis. Cut off the bottom roots of the leeks and slice up the side in order to thoroughly wash the leeks. Chop off the last inch at the green top and discard it. Add the entire leek into the pot. Juice the carrots and celery in a juicer. Pour the juice to the pot. Meanwhile chop up the mushrooms. Cook until the zucchini, leeks and onions are all soft. Ladle some of the liquid from the pot into a mixer. Use tongs to transfer the soft onions, zucchini, and leeks into the mixer. Be careful to leave the beans in the bottom of the pot. In a few batches, blend together the onions, zucchini, and leeks until smooth. Add more soup liquid and the cashews to the mixture, and blend inches. Return the blended, creamy mixture back to the pot. Stir in the TVP and the mushrooms, if desired. Simmer another 20 minutes. Serve and enjoy.